The heart is a focus of interest for clinicians as well as people in the general
population because of the prevalence of cardiovascular disease. Cardiology is the study
of the heart, clinical evaluation of cardiac function and disorders, and treatment of
cardiac diseases. In recent decades, dramatic treatments such as bypass surgery, heart
transplants, and even artificial hearts have become possible. The pervasiveness of
cardiovascular disease ensures that cardiology will remain center stage in the field of
Overview of the Cardiovascular System
The Pulmonary and Systemic Circuits
The cardiovascular system consists of the heart, blood, and blood vessels. Two
main divisions are the pulmonary circuit, which carries blood to the lungs for gas
exchange and returns it to the heart, and the systemic circuit, which supplies blood to all
the tissues of the body.
The right side of the heart is involved in the pulmonary circuit. It receives
oxygen-poor blood from veins and sends it to the lungs via the pulmonary trunk.
Pulmonary veins return the freshly oxygenated blood to the left side of the heart. The left
side of the heart, involved in the systemic circuit, pumps the blood to the huge aorta that
arches off the top of the heart and immediately begins giving off arteries that supply
tissues of the body. The blood returns to the heart via veins that finally converge on the
superior vena cava and inferior vena cava that enter the right side of the heart.
Position, Size, and Shape of the Heart
The heart is located in the thoracic cavity in the mediastinum, between the lungs
and deep to the sternum. It is slightly tilted toward the left. The broad superior portion is
the base, whereas the inferior point is the apex, resting just above the diaphragm.
The pericardium is a double-walled sac that encloses the heart. The outer layer,
the pericardial sac (parietal pericardium), is itself composed of two layers, a superficial
fibrous layer and a deeper serous layer. The tough, durable fibrous layer is made out of
dense irregular connective tissue. The epicardium (visceral pericardium) covers the
surface of the heart. Pericardial fluid, found between the visceral and parietal layers,
lubricates the membranes and allows the heart to beat without friction.
Gross Anatomy of the Heart